During an experiment involving separation, you forget to label your beakers and you are unsure of which beaker contains the aqueous layer and which contains the organic layer. How could you quickly and efficiently determine which one is the aqueous layer?

Would this be the quickest/most efficient method:
Take a small test tube, add roughly 1mL of water. Add a single drop of one of the unknown solutions. If the drop is miscible with water then it is from the aqueous phase; if it sinks to the bottom (or floats) it is the organic layer. Continue with experiment.